The effect of an anti-inflammatory pentapeptide produced by Entamoeba histolytica on gene expression in the U-937 monocytic cell line.

OBJECTIVE: Evaluate the Monocyte Locomotion Inhibitory Factor (MLIF) effect upon the expression of genes encoding human cytokines, receptors and related factors in the human cell line U-937. MLIF (Met-Gln-Cys-Asn-Ser) is an anti-inflammatory pentapeptide produced by Entamoeba histolytica that inhibits many human monocyte functions. MATERIAL AND METHODS: U-937 cell line cultured (24 hrs/RPMI). RNA extracted by Trizol method. 385 genes were analyzed on microarray membranes, complement by real-time RT-PCR and protein expression of some affected genes. RESULTS: MLIF had a preferentially inhibitory effect on gene expression; four genes were over-expressed and 13 underexpressed in MILF vs. simple medium - constitutive expression. Three genes are over-expressed and 19 under-expressed in MLIF/PMA vs. PMA - induced expression. CONCLUSIONS: Many modified genes are products regulated by the Nuclear Factor-kappaB and Mitogen Activated Protein Kinase pathways, suggesting MLIF involvement with these two major pathways for the modulation of the inflammation and immune responses.

Assessing pesticide safety knowledge among Hispanic migrant farmworkers in Oregon.

The purpose of this article is to report on the development and initial use of a pesticide knowledge test (PKT) specifically designed to evaluate agricultural workers' knowledge of the content mandated by the federal Worker Protection Standard (WPS). The PKT is a 20-item, true-false test, used in a sample of 414 adult and adolescent migrant farmworkers in Oregon. The overall mean score, i.e., number correct, was 15.67(78.4%), with both adults and adolescents demonstrating the most difficulty with questions related to the overall health effects of pesticides. The internal consistency was 0.73, when estimated using a method to correct for small sample sizes. Only six items had less than 70% correct answers. Content validity was achieved by basing the items directly on the Worker Protection Standard; face validity was obtained by having the final version of the test reviewed by a bilingual (English-Spanish) educator familiar with the requirements of the WPS. Overall, adult participants scored better than adolescents, and those with previous pesticide training scored better than those without. There were no differences in scores based on gender or whether the test was taken in English or Spanish; however, participants who spoke indigenous languages scored significantly lower than those who did not. These results indicate that the PKT is a valid, reliable measure of worker knowledge of the content of the WPS, although it does not measure the extent to which that knowledge is actually used in the work setting.

Pesticide knowledge and risk perception among adolescent Latino farmworkers.

A substantial proportion of the agricultural production in the U.S. is dependent on the labor of Latino farmworkers. While exact figures are not known, it is estimated that adolescents make up 7% of this valuable workforce. These young workers may be at increased risk for the toxic effects of environmental exposures encountered during their work. Furthermore, language barriers and health beliefs may influence the risk perceptions of this population. We conducted a cross-sectional survey of migrant adolescent farmworkers in 1998 to investigate their work practices, health beliefs, and pesticide knowledge. The large majority of the adolescents in our sample were from Mexico, and 36.3% spoke primarily indigenous languages. Many of the adolescents (64.7%) were traveling and working in the U.S. independent of their parents. Few of the adolescents reported having received pesticide training; however, 21.6% of the sample reported that their current work involved mixing and/or applying agricultural chemicals. The scores on the pesticide knowledge questionnaire were found to significantly predict self-reported use of protection for adolescent farmworkers. The results of this study point to a need for improved pesticide training in youth agricultural workers and specialized education efforts directed toward minorities who speak indigenous dialects. Special attention is merited toward adolescent farmworkers who report that their work includes mixing or applying agricultural chemicals. As the number of adolescent farmworkers increases in the U.S. and the characteristics of the migrant stream continue to change, culturally and developmentally appropriate instruments are needed to adequately assess the health beliefs and protective practices of this population.

Fetal amniotic adhesions. Their topographic concordance with regionally clustered malformations.

BACKGROUND: The amniotic band disruption complex (ABDC) has been segregated recently into various phenotypes. In view of the pathogenic mechanisms that have been proposed, this study was designed to assess if it is one variable process or is composed of several distinct complexes. METHODS: The 48 cases of fetuses with bands or placenta attached to fetal parts cited in this paper included nine new cases and 39 from the literature. They were organized first according to the embryonal topography of the malformations, then according to the position of the adhesions, and finally by the assessment of distances between the cases and between the malformations using the squared Euclidean distances for binary variables and cluster analysis. RESULTS: In all three analyses, three groups were identified: 1) fetuses with cephalo-thoracic anomalies; 2) fetuses with caudal anomalies, and 3) fetuses with mixed anomalies. Nonetheless, overlap among the three groups was apparent. Thus, while fetuses with amniotic bands form three clusters, it appears that these are part of a spectrum and should be considered as variable manifestations of a single entity resulting from a single pathogenetic mechanism. An association was established between the localization of the adhesions and the malformations in various axes. Abdominoschisis, however, was not particularly related to adhesions at one or the other end of the fetus; a short umbilical cord was an almost universal finding. Single umbilical artery (SUA) was especially related to caudal adhesions and malformations (p = 0.004 and 0.001), as well as abdominoschisis (p = 0.002) and agenesis of the abdominal organs (p = 0.008). CONCLUSIONS: The association between amniotic adhesions to the fetus and multiple malformations occurring predominantly in the same area suggest that the former are the cause of the latter. The association of abdominoschisis, as well as a short umbilical cord, with malformations and adhesions in all areas, suggests that these are secondary phenomena to generalized embryonal and fetal tension. SUA, however, with a specifically regional association, is more likely to be due to disruption from exposure in cases with abdominoschisis, often accompanying the loss of abdominal organs.

The ultrastructure of Entamoeba histolytica locomotion.

This quantitative ultrastructural survey of E. histolytica locomotion in Boyden chambers supports the concept that this parasite is capable of random, chemokinetic and chemotactic motility. An E. histolytica committed to chemotaxis will flatten over the filter, accumulate smaller vacuoles at the front of the cell, and will also project pseudopods and its polarized body towards and alongside the chemoattractant axis, respectively. Other cell features such as cell polarization, membrane ruffling, hyaline, total number of pseudopods and caudal displacement of the nucleus appear to be associated with the locomotion efforts as such, perhaps reflecting speed (chemokinesis) but irrespective of orientation (chemotaxis). Finally, only one of the 11 features that were analyzed (i.e., number of vacuoles) failed to be distinctly associated with any of the movement forms studied. E. histolytica appears to possess the full repertoire of locomotion modalities observed in free moving eukaryots, and its motility translates into ultrastructural landmarks that could be useful indicators of subcellular events related to locomotion.

Quantitative assessment of 12-lead ECG synthesis using CAVIAR.

The objective of this study is to assess the performance of patient-specific segment-specific (PSSS) synthesis in QRST complexes using CAVIAR, a new method of the serial comparison for electrocardiograms and vectorcardiograms. A collection of 250 multi-lead recordings from the Common Standards for Quantitative Electrocardiography (CSE) diagnostic pilot study is employed. QRS and ST-T segments are independently synthesized using the PSSS algorithm so that the mean-squared error between the original and estimated waveforms is minimized. CAVIAR compares the recorded and synthesized QRS and ST-T segments and calculates the mean-quadratic deviation as a measure of error. The results of this study indicate that estimated QRS complexes are good representatives of their recorded counterparts, and the integrity of the spatial information is maintained by the PSSS synthesis process. Analysis of the ST-T segments suggests that the deviations between recorded and synthesized waveforms are considerably greater than those associated with the QRS complexes. The poorer performance of the ST-T segments is attributed to magnitude normalization of the spatial loops, low-voltage passages, and noise interference. Using the mean-quadratic deviation and CAVIAR as methods of performance assessment, this study indicates that the PSSS-synthesis algorithm accurately maintains the signal information within the 12-lead electrocardiogram.

The killing of Entamoeba histolytica by activated human eosinophils.

Unlike normal, opsonin aided human eosinophils, fMLP-activated human eosinophils are capable of destroying virulent E. histolytica. Opsonins are not required for this action, although they enhance the effect. Some activated eosinophils succumb in the action as well, probably victims of toxic products released by dying amebas. Activated eosinophils thus appear to resemble activated macrophages in their dealing with this parasite.

Effect of the monocyte locomotion inhibitory factor (MLIF) produced by Entamoeba histolytica upon the respiratory burst of human leukocytes.

In addition to inhibiting the locomotion of human MP, MLIF appears capable of inhibiting the respiratory burst (measured by chemiluminescence) of MP and of PMN as well. The effect on the latter cells may or may not be relevant in the host-E. histolytica interaction, as PMN have been found to be notoriously inefficient in dealing with amebas and, foremost, do not use oxidative mechanisms in dealing with the parasite. On the other hand, the inhibitory effect on MP may represent a true evasion mechanism inasmuch as activated MP are capable of destroying virulent amebas, and do so by both oxidative and non-oxidative mechanisms.

Incongruent parenthood in a Mexican mestizo population as determined by HLA typing.

The incidence of incongruent parenthood was determined by confronting the declared familial relationship of 98 father-mother-son/daughter trinomials (drawn from the Centro Médico Nacional-IMSS (CMN-IMSS) Kidney Transplant Program) with their HLA-A and B antigens. Fourteen (14.3%) discrepant cases were found: three each with the putative father (3.1%) or with the putative mother (3.1%), two with either father or mother (though impossible to determine precisely with whom) (2.0%), and six with both parents (6.1%). Several possible explanations of these findings were considered, such as out-of-wedlock pregnancies, complex known or unknown, declared or undeclared social circumstances frequently related to the population studied (i.e. imminent kidney transplantation) and technical pitfalls. These data underscore the level of possible "noise" and imprecision in population genetics; genetic-epidemiology and transplantation programs.

Development of a template boundary algorithm to determine the ST-T threshold for silent ischemia.

A template boundary algorithm which quantitatively determines ST-T variability has been implemented and tested using seven normal patients. Relatively uniform variability was demonstrated throughout the ST-T segment in these patients during single lead continuous electrocardiographic monitoring at bedrest. The range of variability appears to be a function of both R wave and T wave amplitude. This algorithm appears to have potential utility in defining the ischemic criteria for silent ischemia.

Ultrastructural changes associated with the inhibition of monocyte chemotaxis caused by products of axenically grown Entamoeba histolytica.

The supernatant fluid of axenically grown Entamoeba histolytica-HM1 significantly modifies the ultrastructural features associated with monocyte chemotaxis as assayed in Boyden chambers. This morphological evidence supports the existence of a factor, monocyte locomotion inhibitory factor (MLIF), produced by E. histolytica that inhibits the in vitro locomotion of human monocytes. None of the leucocyte-locomotion modifying drugs included in this study (i.e., cytochalasin-B, colchicine, vinblastine, and hydrocortisone) caused changes totally comparable with those induced by MLIF. The most striking feature was the increase of centriole-associated microtubules induced by MLIF and by cytochalasin-B. MLIF may inhibit monocyte locomotion by directly inducing excessive microtubule assembly, although a direct, if somewhat weak effect upon microfilaments cannot be excluded. The increase in microtubules could then represent a perhaps futile attempt of the microtubule organizing center to overcome the locomotion blockade that has occurred elsewhere in the cell. If active in vivo, MLIF may contribute to the paucity of inflammation in the advanced stages of invasive amebiasis, and consequently to the lack of scar tissue formation upon recovery from such lesions, as monocytes constitute an essential link to the healing process.